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味精等电母液资源化新方法及过程模拟
其他题名New resource utilization method of isoelectric supernatant in monosodium glutamate production and process simulation
张晓燕
学位类型博士
导师丛威
2007-05-18
学位授予单位中国科学院过程工程研究所
学位授予地点过程工程研究所
学位专业生物化工
关键词电渗析 等电母液 双极膜 资源化 模型
摘要味精等电母液资源化对于实现味精清洁生产具有重要的意义。电渗析具有过程简单、效率高、废物排放少等特点,可为某些物质资源的再生和回收、降低物质和能源消耗、减少废物排放、消除环境污染以及某些酸和碱的分离和制备提供新的途径。 本论文针对味精生产工艺的特点研究了味精等电母液资源化的新方法,考察了电渗析资源化等电母液中硫酸铵和谷氨酸的工艺,并采用不可逆过程热力学方法推导了电渗析的过程动力学模型。 首先探索了从发酵液直接电渗析提取谷氨酸盐、从味精等电母液电渗析脱盐和从味精等电母液电渗析再生酸碱这三种电渗析方案,综合评价后选定电渗析再生等电母液中硫酸铵的方案。 研究了离子交换膜、碱室氨浓度、电流密度、流速和初始酸浓度对双极膜电渗析再生硫酸铵的过程性能的影响。对于选定的膜组合,并采用六室膜堆结构分别测定了阴膜、阳膜的极限电流密度。采用响应面分析法优化了电渗析生产酸碱过程的操作参数,硫酸铵的转化率达到91%以上,平均电流效率为51.9%,能耗为99.2 kWh m-3母液。经无机膜微滤或中空纤维膜超滤等电母液可以提高电渗析的过程性能,采用酸-碱-水的清洗方法可以减缓膜污染状况。 考察了电渗析分离回收等电母液中谷氨酸的工艺。实验表明,改进型普通电渗析可以连续操作从等电母液中分离回收谷氨酸,较高的初始谷氨酸浓度、变压操作模式可以降低能耗、提高电流效率,谷氨酸最高回收浓度可达40 g l-1;用改进型普通电渗析回收的谷氨酸溶液作为双极膜电渗析酸室初始进料液回收双极膜电渗析生产的硫酸,将两步电渗析进行组合可以降低能耗。 采用不可逆过程热力学方法分析流和场的耦合作用,推导出混合电解质溶液电渗析生产酸碱过程中离子和水通过膜的传递方程。在电流一致性条件下,结合离子和水通过膜的传递方程建立了沿腔室流动方向的离子浓度及流速变化的过程模型。氯化钠、硫酸钠溶液电渗析过程各室电解质浓度、溶液体积和电流密度的计算结果与实验结果吻合较好。 用上述模型模拟了操作条件、离子交换膜性能参数和装置结构对电渗析脱盐和再生酸碱的过程性能的影响。模拟表明,双极膜的性能是影响电渗析再生酸碱过程效率的主要因素。适当提高初始进料溶液浓度、选择性能优良的离子交换膜和适宜的电渗析器结构可以提高脱盐效果和再生酸碱的效率。味精等电母液电渗析再生酸碱过程的模拟结果与实验结果相吻合,表明本文建立的模型能够模拟复杂电解质体系的电渗析过程。
其他摘要It is important for resource utilization of isoelectric supernatant in the industry of monosodium glutamate to realize cleaning production of monosodium glutamate. Electrodialysis has been taken increased attention due to its advantages in low energy consumption, high efficiency, convenient operation and minimal pollution, which has been applied in many fields. In this thesis, a new resource utilization method of isoelectric supernatant that aimed at the characters of monosodium glutamate production was developed, and the technology of resource utilization to ammonium sulfate and glutamic acid in isoelectric supernatant by electrodialysis was studied. Based on the irreversible thermodynamics approach, mathematical models that described the desalination and regeneration processes of electrodialysis were developed. First, three schemes of electrodialysis applied in monosodium glutamate production were investigated. According to general estimation, it was found that regeneration of acid and base from isoelectric supernatant by bipolar membrane electrodialysis (BMED) was prior to the schemes of glutamate recovery from fermentation broth and desalination from isoelectric supernatant by electrodialysis. The effects of ion exchange membranes, operation parameters such as ammonia concentration in base cell, current density, flow rate and the initial acid concentration on process performances of bipolar membrane electrodialysis were investigated. Using six-compartment membrane stack, the limiting current densities of anion and cation exchange membranes in the selected membrane combination were measured, respectively. Then, operation parameters for regenerating acid and base from ammonium sulfate were optimized by response surface method. The values of conversion ratio, average current efficiency and energy consumption under the optimal conditions reached 91%, 51.9% and 99.2kWh m-3, respectively. The operation performances were improved by pretreatment of isoelectric supernatant using microfiltration or ultrafiltration, and the effect of membrane contamination was lessened using the membrane-cleaning method of acid-base-water. Scheme and technology for recovering glutamic acid from isoelectric supernatant by electrodialysis were investigated. The results showed that glutamic acid in isoelectric supernatant was separated by the modified traditional electrodialysis. The highest concentration of glutamic acid reached to 40 g l-1. Higher initial glutamic acid concentration and adjusted-voltage operation mode improved current efficiency and decreased energy consumption. The combination of two-step electrodialysis, ie. the modified traditional electrodialysis to recover glutamic acid and bipolar membrane electrodialysis using recovered glutamic acid as initial acid solution to regenerate sulfuric acid, significantly reduced the energy consumption. Based on irreversible thermodynamics approach, the ion and water transport models were set up to describe the transport of ion and water through membrane in the regeneration of acid and base using mixed electrolyte solution by electrodialysis. Furthermore, a mathematical model to describe the concentration of ions and velocity of flow in the flowing direction of cell was developed. The electrolyte concentration, solution volume variation and current density in electrodialysis process using sodium sulfate solution can be predicted well by the model. The effects of operation conditions, characteristics of membranes and construction of electrodialyzer on the process performances of desalination and regeneration of acid and base by electrodialysis were investigated by process simulation using above model. The results indicated that characteristics of bipolar membrane markedly affected the efficiency of electrodialysis. The efficiency of electrodialysis can be improved by increasing the initial concentration of electrolyte solution and selecting the ion exchange membrane with high conductivity and transport number. The results of model simulation of acid and base regeneration processes in isoelectric supernatant under different operation voltages were in accordance with the experimental results, showing that the model could be used to simulate the electrodialysis process in complicated electrolyte system.
页数213
语种中文
文献类型学位论文
条目标识符http://ir.ipe.ac.cn/handle/122111/1182
专题研究所(批量导入)
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张晓燕. 味精等电母液资源化新方法及过程模拟[D]. 过程工程研究所. 中国科学院过程工程研究所,2007.
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